1. Technical Field
The present invention relates to a structure of a vehicle interior illumination apparatus, and more particularly to a structure of a switch of the vehicle interior illumination apparatus.
2. Related Art
A vehicle interior illumination apparatus which illuminates the interior of a vehicle is provided on the ceiling of a vehicle compartment. The vehicle interior illumination apparatus includes a switch for switching operations, such as ON and OFF operations, and a push switch or a slide switch which is disposed on an operation panel of the vehicle interior illumination apparatus is often used. However, such a push or slide switch is small in size and is therefore difficult to locate in a portion with low visibility, such as the ceiling of the vehicle compartment, and therefore has a problem of poor operability. In order to deal with this disadvantage, a structure in which a whole lens surface of an illumination apparatus is formed as a depression surface of a push switch, so that the whole lens surface serves as a switch, has been proposed. However, even with this structure in which the whole lens surface is formed as a depression surface of the push switch, because the switch which is used is a seesaw switch or the like, the switching operation cannot be achieved unless a specific portion of the lens surface is depressed. As a result, a significant improvement in operability cannot be obtained.
In order to overcome the above difficulties, JP 2007-230450 A, for example, proposes a vehicle interior illumination apparatus which aims at improving the operability by providing a touch switch on a lens surface. The vehicle interior illumination apparatus described in this reference provides a switch in which a sheet-like transparent electrode is attached onto a surface of a lens on a light source side, through which light from the light source transmits to illuminate the vehicle compartment, and which controls an ON/OFF operation in accordance with a change in the stray electrostatic capacitance of the electrode caused by a surface of the lens on the vehicle compartment side being touched by a human being. This switch is advantageous in that because power ON and OFF can be achieved simply by touching the surface of the lens of the vehicle interior illumination apparatus on the vehicle compartment side, without direct contact with the electrode, deterioration of the electrode can be substantially prevented so that a switch with a long life and a stable operation can be achieved.
Here, vehicle interior illumination apparatuses provided on the ceiling of the vehicle compartment include, for example, those which operate ON and OFF due to a switching operation performed by a passenger, such as map lamps, and those which turn ON and OFF in conjunction with the operation of a vehicle portion such as a door. However, many of the map lamps developed in recent years are configured to illuminate not only a portion around passenger's hands intensively but also the whole interior of the vehicle compartment. In such a case, two different types of switches are necessary for a map lamp; one switch for turning the lamp ON and OFF by the operation of a passenger and the other switch for switching the linkage state between ON/OFF of the lamp and a door operation, for example.
Referring to FIG. 7, a map lamp 70 of related art includes a case 11 to which a light source such as an illumination lamp is attached, a design panel 12 provided on the vehicle compartment side, and illumination lenses 61 and 62 through which light from the light source transmits. A transparent electrically conductive sheet for a touch sensor is attached on a surface of each of the illumination lenses 61 and 62 on the light source side, so that the light sources corresponding to the respective illumination lens 61 and 62 can be turned ON and OFF in accordance with a change in the electrostatic capacitance caused by a human being touching the surface of each of the illumination lens 61 and 62. A switch console 71 which is provided between the two illumination lenses 61 and 62 of the map lamp 70 includes a lighting mode change switch 72 which is used for switching the states in which the map lamp 70 is/is not turned ON and OFF in conjunction with the opening and closing operation of the door. The switch console 71 includes, on the surface thereof on the vehicle room compartment side, marks 73, 74, and 75 each indicating the position of the switch corresponding to the selected lighting mode. Specifically, the mark 73 indicates a knob position corresponding to a mode in which the map lamp 70 is continuously ON regardless of whether the door is opened or closed, the mark 74 indicates a knob position corresponding to a mode in which the map lamp 70 is turned ON and OFF in conjunction with the opening and closing of the door, and the mark 75 indicates a knob position corresponding to a mode in which the lamp 70 is continuously OFF.
Here, a lever switch is used as the lighting mode change switch 72, so that the switch of the map lamp 70 disposed on the ceiling which provides poor visibility can be operated without visual recognition. However, from a design viewpoint, the map lamp 70 which is formed in a flat plane shape having a switch knob protruding therefrom is not preferable in terms of design uniformity. Accordingly, there has been a desire for such a map lamp having a flat design. In order to meet this desire, it is conceivable, for example, to arrange the touch switches as described in JP 2007-230450 A in the periphery of the illumination lenses 61 and 62. This structure, however, also has a problem that, because it is necessary to provide a great number of touch switches in a narrow region, each touch switch has a small area, leading to a high frequency of erroneous operations.
Therefore, the present invention is aimed at suppressing erroneous operation with respect to the touch switches in a vehicle interior illumination apparatus.